Canon I-Sensys LBP5050, Руководство по обслуживанию

Страница: 39 / 104

Chapter 2
2-13
- Thermal fuse (FU1): Prevents the fixing heater temperature from rising abnormally high
The thermal fuse is located at the center of the fixing heater.
If the temperature of the fixing heater rises abnormally high, the thermal fuse blows to interrupt power supply to the fixing heater.
These temperature controls in the fixing unit are performed by the fixing control circuit and the fixing heater safety circuit according to the commands from the DC
controller.
2.6.2 Various Control Mechanisms
2.6.2.1 Controlling the Speed of the Fixing Unit
2.6.2.1.1 Speed control on small size paper (Throughput down control)
0019-2598
LBP5050N / LBP5050
This is the control to prevent the overheating at the edge of the fixing heater when continuously printing the smaller width paper than A4 size.
When continuously printing the smaller width paper than 210mm (A4 size), the machine slows down the throughput by extending the paper pickup interval
according to the number of print.
T-2-4
2.6.2.2 Fixing Temperature Control
2.6.2.2.1 Fixing temperature control
0018-6519
LBP5050N / LBP5050
The fixing control circuit brings the fixing heater temperature at the targeted temperature.
F-2-19
The DC controller monitors the FIXING HEATER TEMPERATURE (MAINTH) signal and sends the FIXING HEATER DRIVE (FSRD+, FSRD-) signals ac-
cording to the detected temperature. The fixing heater drive circuit controls the fixing heater depending on the signals so that the heater remains at the targeted
temperature.
1) Warm up temperature control
This control is to warm up the fixing heater until the fixing temperature reaches the required fixing temperature.
Warm up temperature differs depending on the elapsed time from the previous print, paper type or environment.
2) Print temperature control
This control is to keep the fixing sleeve temperature at a targeted temperature during printing.
CPU changes the target temperature corresponding to the number of print step-by-step. Target temperature differs depending on paper type.
Paper type Setting on driver
The number of print
1 to 5 sheet 6 to 10 sheet 11 to 20 sheet 21 to 50 sheet Over 50 sheet
Plain paper (75 to 90 g/m2) Plain paper
8 6 5.5 4 2
Thin paper (60 to 74 g/m2) Plain paper L
Thick paper (91 to 120 g/m2)
Think paper 1
6 5 5 2 2
Thick paper (121 to 163 g/m2)
Thick paper 2
MAINTH
/RLD-
FSRD+
RL901
TH802
FU1
/RLD+
FSRD-
Fuse
FU901
DC controller
Fixing control circuit
FU1: Temperature fuse
TH802:Thermistor
Fixing
heater
(H801)
Pressure
roller
Fixing film unit
Fixing unit
Fixing heater
safety circuit
Fixing heater
drive circuit
Relay
drive
circui